The objective of this project is the research and development of suitable analytical methods to: (1) establish the structure and purity of potential anti-AIDS agents and new antiviral drugs, (2) determine physical, chemical and biochemical properties, including octanol-water partition coefficients, of these compounds and their metabolites, and (3) measure these drugs and their metabolites in biological samples to elucidate pharmacology and to determine pharmacokinetics. High- performance liquid chromatography and mass spectrometry are emphasized techniques. Sugar-fluorinated dideoxynucleosides, including 2'-F-ddA and prodrugs of 2'-F-ddI and 2'-F-ddG are currently the compounds of primary interest. The role of adenosine deaminase in prodrug activation is also under investigation. An HPLC method for measuring both 2'-F-ddA and 2'- F-ddI in plasma, urine and cerebrospinal fluid has been adapted for narrow-bore HPLC. This method has been applied to determine serum levels in Hu-PBL-SCID mice after chronic oral administration, to measure peak plasma levels in rats after bolus dosing, and to study central nervous system penetration in rats. 2'-F-ddA exhibits less catabolism in vivo than its non-fluorinated analogue and enhanced plasma exposure for an equivalent dose.